Method GetTimeline

internal/patroni/api.go:175–208

GetTimeline gets the patronictl status and returns the timeline, currently the only information required by PGO. Returns zero if it runs into errors or cannot find a running Leader pod to get the up-to-date timeline from.

(ctx context.Context)

// Returns zero if it runs into errors or cannot find a running Leader pod
// to get the up-to-date timeline from.
func (exec Executor) GetTimeline(ctx context.Context) (int64, error) {
	var stdout, stderr bytes.Buffer

	// The following exits zero when it is able to read the DCS and communicate
	// with the Patroni HTTP API. It prints the result of calling "GET /cluster"
	// - https://github.com/zalando/patroni/blob/v2.1.1/patroni/ctl.py#L849
	err := exec(ctx, nil, &stdout, &stderr,
		"patronictl", "list", "--format", "json")
	if err != nil {
		return 0, err
	}

	if stderr.String() != "" {
		return 0, errors.New(stderr.String())
	}

	var members []struct {
		Role     string `json:"Role"`
		State    string `json:"State"`
		Timeline int64  `json:"TL"`
	}
	err = json.Unmarshal(stdout.Bytes(), &members)
	if err != nil {
		return 0, err
	}

	for _, member := range members {
		if member.Role == "Leader" && member.State == "running" {
			return member.Timeline, nil
		}
	}

	return 0, err
}